This invention relates to dipole TV receiver antennas, and is directed particularly to insulators for insulating and supporting the element rods of such antennas with respect to one another and with respect to the booms along which the dipole elements of such antennas are arranged.
The use of one or more dipole elements, each of which comprises a central insulator and a pair of opposed element rods spaced along a horizontally-extending support boom, is well known in TV receiver antenna construction. Various multiple arrangements of such dipoles secured along a common support boom to achieve the desired electrical characteristic ratios of bandwidth to signal gain are also known. Such TV assemblages or "arrays", because of their size, utilize dipole constructions the element rod of which, for storage and transportation purposes, can be pivoted or "folded" inwardly against the common supporting boom. Upon installation of the dipole TV antenna, the dipole element rods are "unfolded", or swung outwardly about their insulator pivot points, to their extended positions of use. To enable such pivotal swinging of dipole element rods with respect to their common, central insulator, resilient metal clips of one kind or another, fixed either with respect to the pivotal inner end of a dipole element rod, or with respect to an outer end portion of the insulator, serve to cooperatively snap-fit as a detent when the pertaining dipole element rod is moved to its predetermined, extended position of use. Such a dipole element and insulator is exemplified in U.S. Pat. No. 3,605,103 to Simons, wherein separate resilient clips secured at the inner ends of the dipole element rods ar formed with tail-pieces adapted to snap into slots formed in the dipole element supporting insulator when the element rods are turned about their pivot points to their outstretched positions of use. Such previously known dipole element insulators are deficient in various respects, principally in their use of extra positional locking clips or the like in the detent or snap-fit mechanism for removably retaining their associated dipole element rods in the extended position of use. Such extra parts, usually formed of sheet metal, not only are apt to undesirably add to the distributive parasitic capacitance of the individual dipoles and the dipole array constituting the TV antenna, but are also subject to metal fatigue caused by wind induced stresses, with the likelihood of premature mechanical breakdown.
It is, accordingly, the principal object of this invention to provide a novel and improved insulator for the foldable elements of dipole TV antennas that obviates the deficiencies of such insulators heretofore known.
A more particular object of the invention is to provide a dipole element insulator of the above nature, the dipole element rod detent mechanism of which is integrally incorporated in the monolithic design of the insulator itself, and is therefore devoid of extra parts such as spring clips and the like, whereby any deficiencies such as early metal fatigue breakdown and added distributive capacitance associated therewith, are obviated.
Another object is to provide a dipole element insulator of the character described which is integrally formed, such as by injection molding, of a substantially rigid, but somewhat resilient, synthetic plastic material such as polypropolene, the opposed dipole element rod supporting arms of which are provided with a marginal U-shaped, outwardly-extending portion resiliently removable with respect to the main body of the insulator and having, along its outer margin, a ramp and locking slot operative as a detent in retaining an associated pivotally supported dipole element rod in an extended position of use.
Yet another object is to provide an improved dipole element insulator of the above nature which will be comparatively inexpensive to manufacture, uniquely functional in operation, environmentally resistant, and durable in use.